lausvi wrote on 2021-01-19, 16:47:

Hiya. […]
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Hiya.

Ok, I have a Roland SC-55 and a Roland UM-One MkII USB-MIDI interface.

From time to time, I would just like to connect the SC55 to my MacBook (running Big Sur) and play some MIDI files. Are there any good players for just basic playback of MIDI files? So far I have only found MIDITrail, but it doesn't have playlists, and I really don't need that visualizer stuff, I'd just like to play the files! Also it seems that recently MIDITrail, if let playing on background gets stuck randomly (when switching back to it's window, it continues).

Couple of the other free apps I've come across don't let me select the MIDI output device, so I get silence.

Any good (and free!) apps?

You need to use Apple Audio MIDI Setup to set up your MIDI routings on a modern Mac; this is not completely done directly from the apps.

yawetaG wrote on 2021-01-20, 10:16:

You need to use Apple Audio MIDI Setup to set up your MIDI routings on a modern Mac; this is not completely done directly from the apps.

Thanks, that's what I was expecting, but I've yet to get it set up correctly (ie. no sound thrue the Rolands). I'll have another look!

You could try Quicktime Player, which is included with your Mac. It should be able to play General MIDI files, normally using its internal synth, but I think you can also change the settings to use a MIDI out port instead.
Edit: apparently it depends on the version of Quicktime whether it can play GM files or not. Up to Quicktime 7 it is possible, later versions can't do it anymore, and it also depends on the version of Quicktime whether you can choose external MIDI out...

But another option is to drag to file into GarageBand, and then use the IAC driver in Audio MIDI setup to set up MIDI IN and OUT for GarageBand.